One of the common practices in IE is to separate processing into several stages, among which NER is typically employed as the first step [1]}. On the one hand, NER requires a deeper analysis than key word searches, because the semantics of entity mentions are influenced by their contexts. For example, `Washington' may refer to a person, a city, a state, or an organisation, depending on the contexts. On the other hand, NER does not seek to fully understand every aspect of the text, such as the writer's communicative intent [2]}. Therefore, it focuses only on relevant words and ignores the rest. Because of its location at a midpoint on this spectrum, NER is a fundamental task, and it has received considerable attention in the last several decades.
